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Abstract:

A media delivery assembly in which a defined compensating pressure is
established at the backs of included axially adjustable rotors and a
control valve is provided for establishing the compensating pressure at a
predetermined value between a pressure on the pressure side and a
pressure on the suction side.

Claims:

1. A rotary piston machine, comprising:a shaft rotor;a counter rotor, the
shaft rotor and the counter rotor having respective axes of rotation
which are arranged at a particular axial angle to one another;mutually
meshing gears on mutually facing front sides of the shaft rotor and the
counter rotor facing one another and limiting working chambers
therebetween;a machine housing in which the shaft rotor and the counter
rotor are supported radially and axially,a suction connection and a
pressure connection in fluid communication with the working chambers at
respective positions of a rotational cycle of the shaft rotor and the
counter rotor, said respective positions being selected to provide
suction and pressure at the suction connection and the pressure
connection, respectively, when the shaft rotor and the counter rotor are
rotated;at least one of the rotors in the machine housing being mounted
in an axially displaceable manner in a direction of the axis of rotation
of the counter rotor, said at least one of the rotors which is axially
displaceable being rotationally arranged in a plain bearing bush provided
in the machine housing; andstructure defining a control space provided in
said housing, said control space being in fluid communication with the
working chambers, said control space being formed on a section of the
counter rotor that is averted from the working chambers and that extends
into the plain bearing bush, such that an axial adjusting force is
provided by fluid transferred from the working chambers to the control
space which acts on the extended section of the counter rotor that
extends into the plain bearing bush, such that force brought about by
working pressure in the working chamber is counteracted.

2. A rotary piston machine according to claim 1, wherein said at least one
of the rotors which is axially displaceable is guided axially and
radially in the correspondingly cylindrical control space of the machine
housing.

3. A rotary piston machine according to claim 1, wherein the fluid, when
pumped, generates the adjusting force.

4. A rotary piston machine according to claim 1, wherein one of the rotors
is constructed spherically on a side thereof averted from the working
chambers, and is supported in a correspondingly spherical recess in the
housing.

5. A rotary piston machine according to claim 1, wherein one of the rotors
includes a spherical surface in a radially central region of the axial
front side thereof, the spherical surface being supported at a
corresponding spherical radially central recess at a remaining one of the
rotors, forming a radially inner boundary of the working chambers.

6. A media delivery assembly comprising a driving rotor and a driven rotor
driven by the driving rotor, each rotor being rotatably mounted in a
rotor housing and interacting by meshing with each other by way of spur
gears, at least one of the two rotors being axially adjustable and
subjected to a compensating pressure at the back thereof, facing away
from the other rotor, and a control valve controlling the compensating
pressure so as to set the compensation pressure at a predetermined value
between a pressure on the pressure side and a pressure on the suction
side.

7. The media delivery assembly according to claim 6, wherein the control
valve comprises a control plunger and three control chambers that are
separated from each other by the control plunger, the pressure of the
pressure side is applied to the first control chamber of the control
valve and the pressure of the suction side is applied to the second
control chamber, and the third control chamber is adapted to be
fluidically connected to the first control chamber or to the second
control chamber by way of a control channel provided on the control
plunger.

8. The media delivery assembly according to claim 7, wherein an inlet
cross-section of the control channel is variable as a function of the
position of the control plunger.

9. The media delivery assembly according to claim 8, wherein the control
plunger extends through a through-channel between the first and second
control chambers, and the variable inlet cross-section of the control
valve is achieved by partial coverage of the inlet cross-section by the
wall of the through-channel.

10. The media delivery assembly according to claim 6, wherein, at the end
facing away from the inlet cross-section, the control channel opens into
the third control chamber.

11. The media delivery assembly according to claim 6, wherein the control
valve is a proportional valve.

12. The media delivery assembly according to claim 6, wherein pressure
from two mutually counteracting valve springs is applied to the control
plunger.

13. The media delivery assembly according to claim 6, wherein the control
valve is attached to the rotor housing.

14. The media delivery assembly according to claim 6, wherein the control
valve is integrated in the rotor housing.

15. The media delivery assembly according to claim 6, wherein the pressure
of the third control chamber is fed via a flow connection to the backs of
the rotors.

16. The media delivery assembly according to claim 6, wherein the driving
rotor and the driven rotor have cycloid gears.

17. The media delivery assembly according to claim 6, wherein the driving
rotor and the driven rotor have trochoid gears.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application is a Continuation-in-Part application of prior U.S.
Nonprovisional patent application Ser. No. 11/597,436, filed Jan. 25,
2007, which was the National Stage of International Application No.
PCT/DE2005/000934, filed May 19, 2005, and which claimed the benefit of
German Patent Application No. 10 2004 026 048.6, filed May 25, 2004;
whereby each of the aforementioned prior applications is incorporated by
reference herein.

BACKGROUND OF THE INVENTION

[0002]The invention starts out from a rotating piston machine, which can
operate as a pump, a compressor or an engine. In the case of a known
rotating piston machine of the generic type (German patent 42 41 320,
European patent 1,005,604), a high leakproofness between the working
chambers is aimed for also by means of the configuration of the teeth, in
order to keep the leakage as small as possible from one working chamber
to the adjacent working chamber over the flanks with line contact between
driving a driving rotor and a driven rotor and vice versa. In this
connection, the crests of the tooth of one rotor proceed linearly at the
flanks of the other rotor, the course of the working surface of which is
cycloidal.

[0003]The output, required from such a rotating piston machine, varies
depending on the use, to which it is put. For this purpose, different
control and regulating methods are known. The simplest method is to
combine the pressure and suction sides of the machine. However, with
regard to the high energy taken up by the machine, this makes hardly any
difference. In many cases, especially when used as a lubricating pump in
the motor vehicle sector, but also when used as a presupply pump for a
diesel fuel injection system, every effort is made to keep the energy,
taken up by the machine, as low as possible and to adapt it to the actual
power output (see German Offenlegungsschrift 100 25 723).

[0004]In comparison to the above, the inventive rotating piston machine
with the characterizing distinguishing features described herein has the
advantage that the energy, taken up by the rotating piston machine,
corresponds directly to the power output of the same. A leakage loss of
such a machine, which can never be avoided completely, has become a
quantity control or loss quantity control, which is brought about by a
selective change in the gap width. A further advantage consists therein
that foaming, which may arise, for example, when controlling the return
channel, is largely prevented, for example, when fuel or oil is pumped.

[0005]It is known that, by connecting the suction side with the pressure
side directly (DE 100 25 723), a corresponding decrease in energy uptake
can be achieved in fuel pumps. However, such systems do not involve
working chambers located on the front faces of the rotors and, instead,
are concerned with gear pumps with radially disposed cogs or annular
gears with a completely different mode of operation from the very start
(displacement in the axial direction), so that such variously known
solutions cannot be used for the invention. Accordingly, for an oil pump,
which also works with a gear wheel and an annular gear, it is known (U.S.
Pat. No. 5,085,187) that the pump working chambers may be closed off
laterally by a lid, which is shifted when the pumping pressure is
sufficiently high, so that a connection is established between the
suction space and the pressure space of the oil pump.

[0006]For adapting the energy uptake to the actual power output of
rotating piston machines with gearing at the front (U.S. Pat. No.
2,049,775), it is known that the driven rotor may be swiveled within a
spherical bearing, in order to change the axial angle between the axes of
rotation by these means, which may lead correspondingly to a change in
the amount pumped up to a zero amount pumped. It is a disadvantage of
such a construction that the costs of construction are considerably
higher and the output capability is more limited. Moreover, above all,
the sealing of the working chambers from the adjusting device is a
disadvantage.

[0007]Additionally, a media delivery assembly is known from DE 103 35 939
A1, comprising a driving rotor and a driven rotor driven by the driving
rotor, which are rotatably mounted in a rotor housing and interact by
meshing with each other by way of spur gears, wherein at least one of the
rotors can be axially adjusted and, to the rear thereof, facing away from
the other rotor, a compensating pressure can be applied by way of a
compensating channel. The compensating pressure both acts counter to the
axial pressure forces developing in the working chambers that are formed
between the rotors, and compensates for forces that would push the two
rotors apart. This ensures that the distance between the rotors does not
change. The compensating pressure often corresponds to the pressure of
the pressure side of the delivery assembly, and thus necessitates
considerably higher forces on the rotors. This produces increased
friction in the bearings and between the rotors. Supply can also be made
to the back of the rotor by way of gap flows. This is disadvantageous in
that an undefined compensating pressure develops, which is dependent on
the leakage flows flowing into the space, or out of the space, behind the
rotor. In this embodiment as well, the amount of compensating pressure is
not ideal for low-friction operation.

SUMMARY OF THE INVENTION

[0008]According to an advantageous development of the invention, at least
the axially displaceable rotor is guided axially and radially in a
corresponding, cylindrical control space of the machine housing. The
displaceable rotor, moreover, is disposed equiaxially with the
cylindrical control space.

[0009]According to an embodiment of the invention, which is advantageous
in this respect, the adjusting force is arbitrarily controllable and
works with hydraulic, gaseous and/or electrical means. It is of decisive
importance that forces on the back of the rotor counteract the pressures
in the working chambers, in order to control the desired axial
displacement of the rotor and, with that, the leakage between the working
chambers.

[0010]According to an additional development of the invention, the
chamber, which is bounded by the back of the rotor, is closed off
pressure tight in order to produce an adjusting force by means of a
liquid or gaseous medium.

[0011]According to a development of the invention, which is advantageous
in this regard, the medium pumped generates the adjusting force. By these
means, the delivery pressure of the machine can be used directly to
regulate the adjusting force. Correspondingly, according to a development
of the invention, there is a connection between the working chambers and
the control space for the medium delivered.

[0012]According to an additional advantageous development of the
invention, one of the rotors (shaft rotor) is constructed spherically on
the side averted from the working chamber and supported in a
correspondingly spherical recess in the housing. The radial support of
the rotor can cut into this sphere in order to fix the axial axis of
rotation of the rotor.

[0013]According to an additional, advantageous development of the
invention, there is, at the rotors in the middle region of the front side
centrally a spherical surface at a rotor. This spherical surface is
supported on a corresponding spherical recess at the other rotor and
forms the boundary of the working chambers radially to the inside. By the
axial displacement of the one rotor, an additional connection for the
leakage between the working chambers is produced over this region.

[0014]Additionally, in contrast, the delivery assembly according to the
invention having the characterizing features described herein is
advantageous in that a defined compensating pressure is established at
the back of the axially adjustable rotor, by way of providing a control
valve, which sets the compensating pressure to a predetermined value
between a pressure on the pressure side and a pressure on the suction
side. The compensating pressure is established as a function of the
particular operating point of the delivery assembly, and specifically is
established at a value which allows the delivery assembly to be operated
with the lowest friction possible. A defined force is applied to the
rotor by way of the pressure established in this way on the rear surface
of the rotor. The pressure on the suction side and the pressure on the
pressure side apply forces to the rotors which work to drive the rotors
apart. Since the pressurized areas remain the same, the ideal
compensating force on the rotors is proportional to the pressure
difference between the pressure side and the suction side. For this
reason, a proportional valve is well suited to compensate for the forces,
and thereby reduce the friction between the rotors, between the rotors
and the housing, and in the bearings. This results in lower wear and
higher efficiency. The compensating pressure can be employed in a
compensating manner either on one rotor, or on both rotors. Furthermore,
different compensating pressures can be produced for the two rotors by
using two proportional valves.

[0015]According to an advantageous embodiment, the control valve comprises
a control plunger and three control chambers that are separated from each
other by the control plunger, wherein the pressure on the pressure side
is applied to the first control chamber of the control valve and the
pressure on the suction side is applied to the second control chamber,
wherein the third control chamber can be fluidically connected to the
first chamber or the second chamber by way of a control channel provided
on the control plunger. In this way, a compensating pressure is
established, which has a value between a pressure on the pressure side
and a pressure on the suction side.

[0016]It is particularly advantageous to design the inlet cross-section of
the control channel so that it can be varied as a function of the
position of the control plunger, as in this way a predetermined pressure
loss is achieved.

[0017]Furthermore, the control plunger advantageously extends through a
through-channel between the first and second chambers, wherein the
variable inlet cross-section of the control valve is achieved by partial
coverage of the inlet cross-section by the wall of the through-channel.
In this way, a predetermined pressure loss is produced at the control
valve.

[0018]It is very advantageous to use a proportional valve as the control
valve, wherein the quotient of the difference between the compensating
pressure and suction pressure and the difference between the pressure on
the pressure side and suction pressure is constant.

[0019]It is also advantageous for pressure from two mutually counteracting
valve springs to be applied to the control plunger, as in this way the
control plunger is restored into a predetermined starting position when
shutting off the delivery assembly.

[0020]It is also advantageous, as provided herein, to attach the control
valve to the rotor housing of the delivery assembly, or to integrate such
valve in the rotor housing.

[0021]Furthermore, the pressure of the third control chamber is
advantageously fed, via a flow connection, to the back of the axially
adjustable rotor, as in this way the compensating pressure established at
the control valve can reach the back of the rotor.

[0022]Further advantages and advantageous developments of the invention
may be inferred from the following description, the drawing and the
claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 shows an embodiment of the leakage loss flow control and
associated flow delivery assembly in longitudinal section.

[0024]FIG. 2 shows the leakage loss flow control and associated flow
delivery assembly of FIG. 1, and which includes a control valve thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025]When referring to FIGS. 1-2, a media delivery assembly 1 is shown in
which an inlay 32 is disposed in a housing 4 so that it cannot twist. A
(driven) counter rotor 3, which interacts with a (driving) shaft rotor 2,
which is driven from outside the pump, is disposed rotatably and radially
guided and axially displaceably in the housing 4. On mutually facing
front sides, the shaft rotor 2 and the counter rotor 3 have meshing
gearings 5, through which working chambers 56 are separated from one
another in a known manner and over which the counter rotor 3 is driven by
the shaft rotor 2. One of the two front gearings 5 has a cycloidal cross
section, in order to form by these means a linear connection between the
gear crests of the other part and this cycloidal surface.

[0026]The working chambers 56, the details of which are not shown here and
the capacity of which changes continuously during the operation because
of the changing angle between the respective axes 6 and 7 of rotation of
the respective rotors 2 and 3, are connected corresponding to their
pumping task via a suction connection 58 and a pressure connection
(analagous to suction connection, and therefore not depicted) with a
suction channel (suction kidney) and a pressure channel (pressure
kidney).

[0027]The counter rotor 3 is disposed rotatably in a plain bearing bush
34. Between the plain bearing bush 34 and the counter rotor 3, a plain
bearing shaft 38 is disposed, which is supported radially and axially in
the plain bearing bush 34 and, together with the counter rotor 3, can be
shifted axially within the plain bearing bush 34.

[0028]The shaft rotor 2 is also supported radially and axially in a plain
bearing bush 36. The hat-shaped end of a drive shaft 8 protrudes between
the shaft rotor 2 and the plain bearing bush 36 and the shaft rotor 2
dips with a corresponding cylindrical section into this hat-shaped
formation. Between the bottom of the hat-shaped section of the drive
shaft 8 and the dipping section of the shaft rotor 2, a spring 46 is
disposed, which, on the one hand, carries along the shaft rotor 2 as the
shaft 8 rotates and, on the other, puts the shaft rotor 2 under a load in
the direction of the counter rotor 3.

[0029]On the side averted from the shaft 8, the housing 4 is closed off by
lids 48 and 50. The lid 48 on the inside is supported on, the one hand,
at the plain bearing bush 34 and, on the other, at the lid 50 on the
outside, which functions as the actual closing part of the housing 4 of
the pump and is secured in its axial position towards the outside by a
retaining ring 52.

[0030]Pursuant to the invention, the counter rotor 3 is displaceable
axially in the direction of its axis of rotation 7. Pursuant to the
invention, this displacement can be accomplished with appropriate means
provided in the form of the pressure which develops in the working
chambers so as to form a corresponding adjusting force which affects the
counter rotor 3. This adjusting force acts counter to a restoring force,
which is formed in the example shown, by liquid, and acts on the section
of the counter rotor 3, which dips into the plain bearing bush 34 and is
averted from the working chambers 56. To control this counter force,
there is a connection (not shown) between these chambers, the forces
having to be matched to one another, especially because of the surfaces
acted upon. According to an advantageous development of the invention, at
least the axially displaceable rotor (in the depicted example, counter
rotor 3) is guided axially and radially in a corresponding, cylindrical
control space 54 of the machine housing.

[0031]An insert 13 is disposed in the inlay 32 in the area of the shaft 8
so as to form a seal. It holds the plain bearing bush 36 axially and,
furthermore, accommodates a plain bearing seal 40, in which the shaft 8
is disposed, so that it can rotate. Moreover, the shaft 8 is supported by
a ball bearing 42 in this inlay insert 13. O-rings 44 provide the
necessary seal between this inlay insert 13 and the inlay 32, as well as
between the inlay 32 and the housing 4.

[0032]With specific reference to FIG. 2, the delivery assembly 1 is used
to deliver fluid or gaseous media, such as fluids or gases. The delivery
assembly 1 comprises the driving rotor 2 and the driven rotor 3 driven by
the driving rotor 2, which are both rotatably mounted in the rotor
housing 4 and interact by meshing with each other by way of spur gears 5.
Each of the spur gears 5 is a cycloid or trochoid gear, for example, but
can of course also be a different type of gear. According to the
exemplary embodiment, in some sections the two rotors 2 and 3 have a
spherical shape at the outer periphery thereof. The driving rotor 2 is
driven by the motor 8, such as an electric motor. For each of the rotors
2 and 3, a rotor bearing 9 and 10, respectively, is provided. Each of the
rotors 2 and 3 are relatively configured so that their rotor axes 6 and
7, respectively, are oriented obliquely relative to each other, i.e.,
they are not aligned. At least one of the two rotors 2 and 3, and
specifically the counter rotor 3, as stated above, is axially adjustable.
Such adjustment occurs as the axially adjustable counter rotor 3 is urged
in the direction of the other rotor 2 by way of a spring element 30. The
spring element 30 is a compression spring, such as a disk spring or
helical spring. This ensures that the rotors 2 and 3 bear on one another
at all times.

[0033]The two rotors 2, 3 are designed to be axially adjustable at the
respective rotor bearings 9, 10 thereof, for example. Working chambers 56
are formed between the rotors 2 and 3, the medium being delivered through
these chambers 56 by displacement. Pressure builds in the working
chambers 56 where the volume is being reduced. This pressure also acts in
the axial direction on the rotor bearings 9 and 10 of the rotors 2 and 3,
respectively. In order to prevent the rotors 2 and 3 from lifting off, a
compensating pressure is applied to the respective backs 2a and 3a of the
rotors 2 and 3 facing away from the other of the rotors 2 and 3. In this
way, the pressure forces acting on the rotors 2 and 3 are at least
partially compensated. This is applied to both rotors 2 and 3 according
to the embodiment, but this can, of course, also be implemented on only
one of the rotors 2 and 3.

[0034]According to the invention, a control valve 14 is provided, which
establishes the compensating pressure acting on the rotor backs 2a and 3a
at a predetermined value between a pressure on the pressure side and a
pressure on the suction side. The suction side is an inlet, which is not
shown, and the pressure side is an outlet, which is not shown, of the
delivery assembly. In this way, the compensating pressure is established
at a predetermined value as a function of the particular operating point
of the delivery assembly, and specifically is established at a value
which allows the delivery assembly to be operated with the lowest
friction possible.

[0035]The control valve 14 comprises a control plunger 15 and three
control chambers 16, 17, 18 that are separated from each other by the
control plunger 15, wherein the pressure on the pressure side is applied
to the first control chamber 16 of the control valve 14 and the pressure
on the suction side is applied to the second control chamber 17, wherein
the third control chamber 18 can be fluidically connected to the first
control chamber 16 or to the second control chamber 17 by way of a
control channel 19 provided on the control plunger 15. The control
channel 19 runs in the direction of the longitudinal extension of the
control plunger 15.

[0036]An inlet cross-section 20 into the control channel 19 can be varied
as a function of the position of the control plunger 15. The inlet
cross-section 20 is formed by at least one inlet opening into the control
channel 19. A plurality of inlet openings are provided at the periphery
of the control plunger 15, for example. The control plunger 15 extends
through a through-channel 22 between the first control chamber 16 and the
second control chamber 17, wherein the variable inlet cross-section of
the control valve 14 is achieved by partial coverage of the inlet
cross-section by the wall of the through-channel 22. At the end facing
away from the inlet cross-section 20, the control channel 19 opens into
the third control chamber 18. The pressure of the third control chamber
18 is fed via a flow duct 24 to the backs 2a, 3a of the rotors 2 and 3,
respectively.

[0037]The control valve 14 can be attached to the rotor housing 4 of the
delivery assembly or integrated in the rotor housing 4. The control valve
14 has two inlets 26, 27 for connecting to the suction and/or pressure
sides of the delivery assembly and an outlet 28 for connecting to the
flow duct 24 leading to the respective backs 2a, 3a of the rotors 2 and
3.

[0038]The control valve 14 is designed as a proportional valve, for
example. Pressure from two mutually counteracting valve springs 23, for
example, is applied to the control plunger 15 in order to ensure that it
is returned to a starting position.

[0039]All the distinguishing features, shown in the specification, in the
claims that follow and in the drawing, may be essential to the invention
individually as well as in any combination with one another.